Summary
Published techniques for after-closure analysis of fracturing data usually
assume the presence of a vertical fracture intersecting a vertical well. In
addition, these published techniques usually assume that the formation is
homogeneous. When the formation is naturally fractured or the well is
horizontally intersecting a transverse vertical fracture, those assumptions are
obviously violated and the published analysis techniques might not be
applicable. Through the use of analytical and numerical solutions and
application to actual field data, this paper investigates the analysis of
after-closure data for heterogeneous formations, a naturally fractured
formation, a CBM, and a fractured horizontal well.
This paper briefly reviews the various available techniques for
after-closure analysis, pointing out the strengths and weaknesses of each. An
analytical solution for an injection-falloff test for a naturally fractured
formation has been developed and is presented. This solution might be used to
analyze data for a minifrac test in a naturally fractured formation where the
fracture has healed. Numerical simulation validated the developed solution for
a fracture that has healed. The same numerical simulator was used to expand the
solution to a situation where the fracture maintains residual conductivity.
The solution for a minifrac test in the case of a transverse fracture is
also presented and discussed. Using a numerical simulator, minifrac tests are
simulated and analyzed for both heterogeneous formations and fractured
horizontal wells. Guidelines for the analysis of such data have been developed
and presented.
Field data are also presented. One case presents a minifrac test for a
heterogeneous formation. A case for a transverse fracture intersecting a
horizontal well is also presented and analyzed. A third case for CBM is
discussed.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
3 March 2009
- Meeting paper published:
5 October 2009
- Revised manuscript received:
10 June 2010
- Manuscript approved:
21 July 2010
- Published online:
14 October 2010
- Version of record:
17 November 2010